I was thinking that too, but I think Jerec may be able to control his power better. Iirc his Force blasts were pretty leet and he had advanced skills in various Force applications.
For what it's worth, Coruscant Nights depicted a scene in which Nick Rostu sensed far greater power in Vader than Vastor; whereas Tash Arranda sensed only slightly less power in Jerec than in Vader (Galaxy of Fear: Spore).
__________________ Recently Produced and Distributed Young but High-Ranking Political Figure of Royal Ancestry within the Modern American Town Affectionately Referred To as Bel-Air.
Nick Rostu shouldn't be a very credible source when it comes to sensing force power.
Id give this to Kar.
__________________ "You must begin by gaining power over yourself; then another; then a group, an order, a world, a species, a group of species... finally, the galaxy itself."
- Darth Plagueis
"She may be small but she packs a punch and when shes in this mood...she goes for my danglers" - Oghren, Dragon Age
I would go with Vastor in this. Jerec was defeated by a young, largely untrained Katarn, even while being powered by the Valley of the jedi. Vastor was at least on an even footing with Mace Windu as of Shatterpoint.